WOF: What's your favorite 'geek' movie of all time?

[Weekend Open Forum] The last couple of decades have brought about a number of movies that in one way or another try to capture geek psychology and culture. We've seen everything from the hilariously misconceived hacker that can get into any computer by frantically typing random commands until the words 'access granted' appear on-screen (I'm looking at you Hugh Jackman), to a few gems that hit closer to the mark of portraying what it's like to be a geek or an outsider.

Our question for you today is simple: What's your favorite geek movie of all time? It doesn't need to be strictly related to computers -- fans of science fiction, comedy, fantasy, superhero, documentary or whatever genres are welcome. A few examples to get you started: Sneakers, Pirates of Silicon Valley, and Office Space.